Passenger automobiles today commonly include outside rearview mirrors on both the driver and passenger side of the vehicle. These mirrors are typically adjustable both vertically (up/down) and horizontally (left/right), using electric motors controlled by the driver via a mirror position switch. Usually, a single switch assembly is used which includes a joystick type switch for directing the two-directional movement of the motors as well as a left/right selector switch that switches between the two exterior mirrors so that they can be adjusted one at a time, independently of each other. The selector switch may also include a locked position so that movement of the joystick does not activate either of the mirror motors. On vehicles provided with memory positioning, the mirrors can be automatically moved by suitable vehicle circuitry to a preset position established by the driver. Such circuitry can be implemented using position sensors on the mirrors to determine the instantaneous position of the mirrors in both the horizontal and vertical directions. These types of mirror positioning circuits are well known.
Normally, the driver and passenger side exterior mirrors are adjusted individually by the driver, as mentioned above. However, it has been proposed to provide automatic adjustment of the passenger side exterior mirror based on positioning of the driver side mirror. It is a general object of this invention to provide an exterior rearview mirror system of this type in which adjustments made by the driver to the driver side exterior mirror can be detected and used to automatically make similar adjustments to the passenger side exterior mirror so as to provide the desired field of view through the passenger side mirror without requiring independent adjustment of the passenger side mirror by the driver.